The present invention relates to a semiconductor device manufacturing method and a mold die.
During a process for manufacturing a semiconductor device, a mold die is employed to seal the semiconductor device with resin in order to assure that its external shape is maintained and that the required degree of moisture resistance is achieved. Such resin-sealed semiconductor devices are sometimes held and connected by a lead frame or a substrate. However, a structure that uses a lead frame or a substrate is bound to result in the overall size of the semiconductor device becoming excessively large compared to the size of the semiconductor element itself. Therefore, in recent years, external terminals have been provided as bumps on the semiconductor element substrate.
The following is an explanation of a semiconductor device manufacturing method in the prior art that is implemented by providing external terminals as bumps on the semiconductor element substrate.
External terminals are formed as bumps on a semiconductor element substrate on which semiconductor elements are formed. This semiconductor element substrate is mounted on a mold die comprising an upper die and a lower die, and is sealed with resin covering the external terminals, by injecting the sealing resin through a sealing resin intake formed at a specific position.
As a means for ensuring that the upper portions of the external terminals are exposed from the sealing resin to allow electrical connection of the external terminals, the upper die may be placed in close contact with the external terminals to prevent the external terminal upper portions from becoming covered by the sealing resin. However, it is not desirable to place the upper die in close contact with the external terminals since this will result in an excessive degree of clamping force applied to the semiconductor element substrate where the external terminals are formed to cause deformation of the external terminals and damage to the semiconductor element.
For this reason, during the resin sealing process, the upper portions of the external terminals are temporarily covered by the sealing resin, and then the upper portions of the external terminals are exposed in a subsequent polishing process. Thus, in the semiconductor device manufacturing method of the prior art for manufacturing a resin-sealed semiconductor device, the polishing process, as well as the resin sealing process, is essential, and the inclusion of the polishing process in the manufacturing method results in an increase in production costs due to a greater number of processes to be implemented and a reduction in yield caused by deformation of the external terminals and damage to the semiconductor element.
An object of the present invention, which has been completed by addressing the problems of the semiconductor device in the prior art discussed above, is to provide a new and improved semiconductor device manufacturing method and a new and improved mold die, that make it possible to expose the upper portions of external terminals with a high degree of ease without having to implement a polishing process.
In order to achieve the object described above, the semiconductor device manufacturing method according to the present invention comprises a step in which external terminals are formed as bumps on a semiconductor element substrate, a step in which the semiconductor element substrate is mounted on an upper surface of a lower die of a mold die comprising an upper die and the lower die that is employed to seal the semiconductor element substrate with a resin, a step in which a cushioning member is placed over the area of the upper surface of the lower die where the semiconductor element substrate is mounted and a step in which the upper die is placed in close contact with the external terminals.
Alternatively, the semiconductor device manufacturing method according to the present invention comprises a step in which external terminals are formed as bumps on a semiconductor element substrate, a step in which the semiconductor element substrate is mounted on an upper surface of a lower die of a mold die comprising an upper die and the lower die, that is employed to seal the semiconductor element substrate with a resin and a step in which the upper die is placed in close contact with the external terminals by sliding the upper die and/or the lower die along the direction of the height of the semiconductor element substrate.
In addition, the mold die according to the present invention, which comprises an upper die and a lower die used to seal in resin a semiconductor element substrate having external terminals formed as bumps, is characterized in that a cushioning member is provided to absorb the clamping force imparted by the upper die and the lower die in the area of an upper surface of the lower die where the semiconductor element substrate is mounted.
Another mold die according to the present invention, which comprises an upper die and a lower die used to seal in resin a semiconductor element substrate having external terminals formed as bumps, is characterized in that the upper die and/or the lower die is provided with a sliding mechanism that slides in relation to the direction of the height of the semiconductor element substrate.